A wind turbine known in the art comprises a tapered wind turbine tower and a wind turbine nacelle positioned on top of the tower. A wind turbine rotor with a number of wind turbine blades is connected to the nacelle through a low speed shaft, which extends out of the nacelle front as illustrated on FIG. 1.
Large modern wind turbines get bigger and bigger all the time and the different components of the wind turbine such as the gearbox, generator, braking system etc. do also get bigger. Furthermore, the technological development produces components and interaction between components which are more and more specialized and complex. This is of course advantageous regarding efficiency and output of the wind turbine but since these large wind turbines are expensive and breakdowns can be very costly it is important to ensure that the life, durability, quality, capacity etc. of the wind turbine components are well documented.
One way of doing this would be to gather information on exciting wind turbines and then base the maintenance program, the choice of components and so on, on a statistical analysis of these data. But this method is rather inefficient in that if the data reveals that a component with an expected life of 20 years only lasts an average of 7 years, the similar wind turbines produced in these 7 years will also contain the defective component, and the data can most often not disclose whether the component breaks down because of poor quality, if it has been mounted or used wrong or if several interacting factors causes the reduced life.
Another way of solving this problem is disclosed in European patent application No EP 1 564 405 A1. This application discloses a test bench for carrying out fatigue and load tests on the structural members of primarily the nacelle and the nacelle components. But testing the strength of the structural members of the nacelle has the main purpose of reducing the use of material or optimizing the design of these structural members, hereby reducing the cost and weight of the members and ensuring that they can withstand the loads that they are affected by during normal operation of the wind turbine. It will not provide helpful information regarding selection of components, the interaction of components and other which could prevent breakdowns and reduce the cost of the components.
It is therefore an object of the invention to provide for an advantageous and efficient technique for testing wind turbine equipment.
Especially, it is an object of the invention to provide for a technique for testing wind turbine equipment which offers more realistic load types.